Unloading valve



,1 G. A. CORMIER 2,614,580

UNLOADING VALVE 3 Filed July 17, 1947 T0 SYSTEM IN VEN TOR.

Patented Qct. 21, 1952 UNLOADING vALvE ;Gerard A. Cormier, Springfield, Vt, assignor to Jones & Lamson Machine Company, Springfield, Vt., a corporation of Vermont Application July 17,1947, Serial No. 761,599"

The present invention relates to a pressure regulating valve and relates more particularly to i an unloading valve for use in hydraulic systems.

In many hydraulic'a'pplications itis necessary to maintain working pressure within predetermined limits.- In combination with an accumusomms. ((21. 137-474) lator a pump may be used to supply'oil or other fluid-at a substantially constant pressure to a suitable pressure utilizing system. As is well known, the. pump may be connected to the system including} an accumulator, .when needed, and when the pressure ,attains a predetermined value the pump ,maybe'relieved directly to the supply tank or low pressure port. Meanwhile the accumulator supplies the needed pressure until such pressure falls to a predetermined low value, at which time the pump may be reconnected to; the system. In a valve to automatically accomplish the above, it is desirable that the difference between the high and lowpressures at which the valve operates be readily adjustable; It is also desirable that the absolute value of the maximumand minimum points be independently adjustable; Heretofore valves have been proposed in which one or more of these variables, has been permanently determined for a given valve by the diameter of a bore, a difierential in the diameters of passageways, or the like.

It is, therefore, an object of the present invention to-- provide an unloading valve which is easily adjustable to provide a desired range of working pressure.

' .A further object of vide a valve-in which the minimum setting and maximum setting at which the valve operates may be independently adjusted.

These and other objects and advantages of the present invention will becomereadily ap parent from the following detailed specification, read in connection with the accompanying drawing wherein like reference numerals denote like elements, and in which Fig. 1 is a schematic representation of the valve illustrating the operating elements; and

Fig. 2 is a detail of a portion of Fig. 1 showing the double acting ball valve.

.Referring more particularly toFig. 1, a valve body 3 is provided ha'vingtwo main bores 4 and 5 with interconnecting passageways 6 and 5'. There are also provided three ports, admin 3, ahigh pressure supply port 9, a port l0 leading to a pr'essure utilizing system, and a low pressure this invention is to pro return port H leading to a supply tank; not shown.

The hydraulic system may include an accumulator 52 having a diaphragm i3. When charged by a pump, the accumulator provides a steady supply of pressure to'the hydraulic system in a well-known manner.

' A valve assembly arranged in the bore 4 comprises a ball i-i seated on a stern l5 which'is movable axially and is urgedto'the'right, thus holding the ball hi against ball seat H by a minimum pressure springl 6. Coaxial with stem id and independently slidable thereon, is piston member 58 which is urged totheright by differential spring it. A ball seat 26, having the same diameter as the seat ll, limits the movement of the ball it to the left as will hereinafter be explained. a

A check valve in the bore 5 comprises a ball 2% normallyurged against ball'seat i2 byspring 'Also contained in bore 5 is a valve Zdaurged against seat by a spring 26.. At the left end of bore 5 is a valve unloading member 21 adapted to actuate the valve 23 as will be explained.

In operation with the elements positioned as shown in Fig. l, fluid underhigh pressure from a suitable pump is supplied through port 9 and the check valve com'prising'ball El and spring 23 to the system and the accumulator l2. The pressure thus developed in accumulator I2 is also built up against ball it through interconnectmg passagewayl. It can be seen that the movement of ball It to the left is resisted by the combined pressures of spring 56 and spring l5 as a portion of piston 38 engages a shoulder 28 on the stem 85. I

When the pressure in the accumulator l2 has risen to a predetermined maximum value which just exceeds the combined pressures of springs iii and is, the ball M will move {to they left and leave ball seat l'l.- The instant that this happens, this pressure will appear in passagewayii and will be applied 'to piston member wand to the valve unloading member 2i. Due to the 'rel atively large area of the piston [8, it will move forcibly to the left; thus removing the pressure of spring as from the sleeve I5 and the ball Id. The onlypressure remaining to urge ball M to the right is the pressure of spring {6, and therefore it completes its travel to the left and becomes seated on ball seat 26'. The pressure in passageway 8 will also force valve unloading member 21 to the right. This'actionwill move the valve zdto the right, compressing spring 26 and opening the pump port 9 to the low-pressure port return II. Ball 2I will be forced to the left onto the valve seat 22, thus preventing the accumulator pressure from being dissipated through the low pressure return port II.

While the accumulator pressure is supplying the needs of the system, the pump is relieved directly to the return port as explained.

Uponreaching a predetermined minimum pressure, determined by the setting of the spring I 6, the accumulator pressure will no longer be able to hold ball I4 to the left against ball seat 20. Spring pressure from sprin I6 will move the ball I I back onto the ball seat II. When this occurs, the pressure in passageway B- and the pressure against piston I8 will be relieved through apertures 36 and passageway 29 in the sleeve I to the drain port 8 which may lead back to a suitable reservoir. This will permit spring I9 to return the piston member I B to the right so that both springs I9 and I6 once'again urge ball I4 to the right against ball seat I I. The spring 26, similarly, will move the valve 24 and the member 21 to the left; thus interrupting the connection between pump port 9 and return port II. The pump is now connected to replenish the supply. of pressure to the system and to the accumulator I2.

It can beseen that the total pressure of springs I6-and I3 will determine the maximum pressure at which the pump will be unloaded or disconnected from the system. It will also be appreciated that the pressure of spring I9 will determine the difierential between the maximum pressure at which the pump will be relieved, and the minimum pressure at which the pump will be reconnected to the system.

It is essential. in the operation of the valve as described that ball I4 be out of hydraulic balance at all times in order to insure positive action. In Fig; 2 an. enlarged view of this part of the assembly is shown with the ball I4 just leaving the ball seat I'I. It can be seen that thepressureon the ball urging it to the'left exceeds the pressure urging it to the right because of area (a) upon which the pressure is inefiective because of the stem I5. This precludes the possibility of the stem I5 leaving the ball to float between the ball seats 20 and I I.

The valve actuating member 21 must have a larger effective area presented to the pressure appearing in passageway 6 than the effective area at'the valve seat 25. Thus with the same pressure in passageway 6 as appears in port 9, the member 21 will be able to force the valve 24 to the right and, in addition, overcome the force of the spring 26.

Independent adjustment of the springs I6 and I9 may be provided for as shown in Fig. 1. A tubular member 35 threadably engages valve body 3 and provides a stop for the differential spring I 9. Upon removal of the acorn nut 33 and lock nut 34, it can be seen that adjustment of member 35 can be made to provide the degree of pressure desiredagainst the piston member I8. This setting will determine the differential in pressure. between the minimum and maximum values and may then be secured by lock nut 34. The setting of the spring I6 may then be accomplished by adjustment of the screw 3 I. This setting puts the desired. spring pressure against the stem I5 and determines the minimum pressure at' which thepump will be reconnected to the accumulator and hydraulic system. The setting ofscrew- 31 may be secured by a lock nut a passageway source and the chamber in which said second 4 '32. The entire assembly is then sealed by the acorn nut 33.

From the above detailed description, it is apparent that I have provided a novel type oi! unloading valve in which the minimum and maximum pressures at which it operates can be independently selected to suit any particularly bydraulic application. v

While-a preferred embodiment of this invention has been described, it is understood that modifications within the spirit and scope of the invention may occur to persons skilled in the art.

I claim:

1. A fluid controlling valve comprising a valve casing having a bore therein, a first annular valve seat in one end of said bore, a second annular valve seat insaid bore opposite said first valve seat, a ball between said valve seats and alternately engageable therewith, a hollow stem extending axially of the bore and engaging said ball, firstspring means. urging said stem against said. ball to seat the latter against said. first valve seat,.second spring means normally urging said stem against said ball to seat the latter against said first valve seat, and a passageway communicating between said first valve. seat and the. chamber in which said first springmeans and said. second spring means are located when said ball leaves said first valve. seat.

2. A valve for controlling a source of fiuidpressure comprising a valve casing having a bore therein, a firstannular valve seat at'which said pressure is applied in one end of saidv bore, a second annular valve seat in. said bore opposite said first valve seat, a ball between said valve seats and alternatelyengageable therewith, a hollow stem extending axially of the bore and engaging said ball, first spring means urging said stem against said ball to seat the latter on said first valve seat against said pressure, second spring means normally urging said stem against said ball to seat the latter on said first valve seat, and communicating between said spring means is located when said ball leaves said first valve seat whereby pressure of said second spring means on said stem is relieved.

3. A device for the regulation of fluid pressure, comprising a valve adapted to open under the influence of a predetermined pressure, first resilient means urging said valve to its closed position, a piston member abutting said valve, second resilient means normally urging said piston-member against said valve to close said valve, and a passageway connecting said pressure-with said piston member" when said valve is in the open position, whereby all force of said secondresilient means on said valve is removed.

4. A device for alternately connectinga source of fiuid under pressure to a pressure utilizing system and to a relief port in response to changes in the pressure in said system, comprising a valve adapted to open under the influence of pressure, first adjustable spring means urging said valve to its closed position against said pressure, a piston member abutting said valve, second adjustable spring means normally urging said piston member against said valve to close said valve, and a passageway connecting said pressure with said piston member when saidvalve is in the open position, during. which time all force of said second spring means on said valve-isremoved.

5. A device for the regulation of fluid pressure, comprising'a valve casing having a boretherein, an. annular valveseatin oneend ofsaid bore,

a ball adapted to engage said valve seat, a stem extending axially of said bore and engaging said ball, first spring means urging said stem against said ball to seat the latter on said valve seat, a piston member slidably mounted on said stem, second spring means normally urging said piston against an abutment on said stem to urge said ball against said valve seat, and a passageway connecting said piston member to said pressure Whenever said ball leaves said valve seat, whereby all force of said second spring means is removed from said ball and stem by said pressure.

GERARD A. CORMIER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 2,484,628 Le Valley Oct. 11, 1949 

